The present invention relates to a new and improved sheet material handling apparatus, and more specifically, to a sheet material handling apparatus having an improved mechanism for feeding signatures from hoppers to a pair of conveyors, an improved mechanism for stitching signatures, and an improved mechanism for trimming signatures.
Known mechanisms for feeding signatures from hoppers onto saddle conveyors are disclosed in U.S. Pat. Nos. 2,251,943 and 3,481,594. The signature feed mechanisms disclosed in these patents include a rotatable extractor drum having a gripper which grips a folded edge portion of a signature disposed in a hopper. The extractor drum moves a gripped signature from the hopper along an arcuate path until the folded edge portion of the signature engages a stop member. The trailing edge portion of the signature is then engaged by a transfer cylinder and moved to an opener cylinder. The opener cylinder cooperates with the transfer cylinder to open the signature over the saddle conveyor. The signature is then deposited on the saddle conveyor.
Both of the foregoing patents disclose signature feed mechanisms which transfer signatures from hoppers to a single conveyor. In U.S. Pat. No. 3,544,097 signatures are transferred from a hopper to a pair of flat conveyors. Thus, the signatures are removed from the hoppers by an extractor drum and moved to either one of a pair of transfer drums. Each of the transfer drums is operable to move a signature onto a conveyor. A somewhat different apparatus for transferring signatures from a hopper to a plurality of conveyors is disclosed in U.S. Pat. No. 4,402,496.
It is a rather common practice to stitch or staple signatures as they are being moved by a conveyor. Thus, U.S. Pat. No. 4,196,835 discloses a stitcher assembly which is operable to stitch signatures as they are being moved along a linear path by a saddle conveyor. A somewhat different type of stitcher assembly is disclosed in U.S. Pat. No. 4,641,825.
In addition, there are several known types of mechanisms for trimming signatures. One of these known mechanisms is disclosed in U.S. Pat. No. 3,811,350. This known trimmer includes a front knife which trims the front edge portion of a signature and a plurality of side knives which trim foot and head portions of the signature. In this known trimmer, the side knives are operable to split the signature assembly to form two separate signature assemblies.
Another known trimmer is disclosed in U.S. Pat. No. 3,733,947. This patent discloses a trimmer which is operable to trim books without stopping their forward movement. The trimmer includes a front knife which trims a book while it is on a movable front table. The book is then transferred to a movable side table where side knives complete the trimming of the book.